When the going gets hot

Cement making is a power consuming business. Up to 40% of the energy in a plant is used only for the grinding processes. Even efficient vertical roller mills (VRM) offer an optimization potential by a better and more reliable measurement.

Hot and most dusty gases from rotary kiln, pre-heater tower and clinker cooler can be measured faster, accurately and without any maintenance which opens a huge potential for combustion optimization like the kiln ID fan control.

Typical PROMECON projects in cement production:

  • Control of the transportation air in VRM`s
  • Control of the kiln ID-fan to stabilize complete pyro process
  • Gas balance by the clinker cooler
  • Gas balance by the waste heat recovery (WHR) systems
  • Complete consultancy and egineering solution including project magagement
Gas flows in modern cement plant

Raw mill
The required air flow of a raw mill depends upon the raw material mass flows as well as the moisture. Air flow control of the raw mill is very important since the ID fan consumes almost 60% of the energy of the mill. With PROMECON technology air flow measurement can be installed after the cyclones or directly behind the separator. The total air flow through the VRM can be measured very precisely and controlled for efficient and smooth operation. Usually 1 kWh per ton of raw meal can be reduced by optimized air volume during operation.

Bypass gas
Depending on the fuels fired in the pyro process on kiln- or calciner burner  the operation needs bypass systems which extract certain amounts of gas containing higher sulfur or alkaline concentrations from the process. The exact amount of gas taken out from the energy cycle is not known usually. This can be measured by the MECONTROL Air system - maintenance and drift free. 

Preheater downcomer duct – kiln-ID fan inlet
Measuring the actual exhaust gas flow from the kiln opens up new possibilities for controlling the overall draft through the system. The MECONTROL Air System offers an accurate and drift free flow metering solution without additional pressure drop in the downcomer duct. This results in a more flat lined kiln operation as compared to conventional %O2 control. The benefit is a reduced fuel consumption by 5%.

Primary air
For direct fired kilns it is critical to maintain a controlled primary air flow to maintain the correct flame shape. Modern highly sophisticated burners need a precise air amount to operate at their optimum.

Clinker cooler vent air/secondary air (indirect)
Correct balancing of the clinker cooler fans (last compartments) can be done with PROMECON technology to optimize online the secondary air and maximize the use of clinker cooler waste heat in the rotary kiln.

Tertiary air (TA)
Up to 60% of the clinker burning fuel is combusted in the precalciners using tertiary air from the clinker cooler. For optimum plant throughput and efficiency the amount of air through the TA duct needs to be balanced with the secondary and primary air through the kiln. PROMECON delivers flow measurement solutions for most TAD ducts covering a temperature range up to 1000°C/ 1850°F.

Finished product (cement) mill
For any mill type air flows need to be controlled tightly. Most existing units are tube mills. Air flowmeters are used to control the mill sweeps and separators for maximizing efficiency. New plants or retrofits have been utilizing vertical roller mills (VRM) to reduce electrical consumption. The total air flow through the VRM must be controlled for efficient and smooth operation. Up to 1 kWh per ton of finished product can be reduced by optimized air volume during operation.